1. Field of the Invention
The present invention relates to a method for validating the operational durability of an automotive component product based upon accelerated laboratory random vibration tests employing the principles of physics-of-failure and damage correlation.
2. Description of the Prior Art
In the automotive industry, sinusoidal vibration testing is frequently used due to the low equipment cost and convenience. However, the random vibration test is more desirable because the vibration loading applied on automotive components during actual operating conditions comprises the combination of several random processes corresponding to several different field driving routes. Therefore, a random vibration test conducted in the laboratory can better simulate field loading conditions. Random vibration tests in product validation process is possible now due to the availability of the random vibration test equipment and facilities.
However, it would be desirable to accelerate the testing time by elevating the random vibration profile in some manner. Most current accelerated testing methods are based on a load analysis approach which evaluates the input load and disregards small amplitude loads, regardless of frequency. This approach may cause significant errors, because failure of a product is a stress driven phenomenon and not load driven. Small amplitudes of load may induce large stresses. A more correct accelerated testing methodology must include the considerations of stress response of the product and material damage properties. This combination can best be implemented using the physics-of-failure approach.
An objective of the present invention is to develop a testing methodology to determine random vibration testing methodologies based on the physics-of-failure and damage equivalence technique such that the vibration damage generated in laboratory testing will be equivalent to the damage induced by random vibration in the field. Based on field random vibration profiles and the desired product life goal, an equivalent random vibration test in a laboratory environment, including the vibration level and test time, may be defined. If a product survives this laboratory test profile, it should survive in the field during the desired life time.